radio problem

[02bonnevilleee]

so i bought a aftermarket radio for my '02 pontiac bonneville and i got all the wires hooked up and stuff no problems but the issue is when i plug in the harness to my radio it automatically turns on even if the key isnt in the ignition and i cant turn it off so i was wondering if anyone has a solution i dont know much about cars so im pretty much clueless on a fix if anyone has a solution it would be greatly appreciated.

[Oldman]

Go online and purchase a wiring harness for installation. This will plug into the existing wiring and then will have all wires labeled to connect to the wiring that came with your stereo. This will make the install much easier and you will still be able to use your steering wheel controls.
To answer your question, you have an incorrect power source hooked up. You need to get a volt meter or test light and find a power supply wire that only has power when the key is on.
If you purchase the harness online, you'll also have the power delay like the factory stereo.

[ddalder]

He doesn't have incorrect power connected. These cars are not like those in the 80's where power is cut when the key is turned off. There is always power at the radio whether it's playing or not and whether they key is off or not. When the key is off and the door is opened, a message is sent to the radio over the data bus to (electronically) turn it off. Even when this happens, the display turns off and audio stops but there is still power to the radio. This is why a module is required to interface aftermarket radios into these cars. They manage power based on commands received over the vehicle data bus.

It's also important to purchase the correct interface module. Some are for the standard Bonneville without an amplifier (SE, SLE) and others are necessary when an external amp is installed (SSEi). Some retain OnStar functionality, others don't. Part of what you choose also depends on whether you have installed your own amp or whether you are just installing a radio into the car but using the factory amp (if your car is an SSEi).

It's probably a good idea to update your profile to include both the year of your Bonneville and trim level so other questions you may have later are easier to answer.